Audio-gd R2R-11 owners using 6xx or 4xx?

As the title states, anyone with experience using the R2R-11 with the Massdrop 6xx or 4xx?
As I'm looking for improved sound, especially the 4xx, I am about to pull the trigger on the Audio-gd R2R-11. Did you find a sweet spot on the jumpers? Does the R2R-11 have hidden jumpers like the NFB11?

Also, someone who has tried it with an Audeze LCD 2C (my next targeted cans), feedback would be appreciated!